Various systems and methods exist for using optical instruments to measure position in a three-dimensional space. These systems and methods may convert the position measurements into digital form and plot the measurements over time to trace various shapes and forms. For example, these systems may operate as a digitizing pointer held by hand and used to trace structures for reverse-engineering, sizing purposes, medical procedures, or motion tracking.
A variety of commercially available optical digitizer systems are available that determine x, y, z coordinates of markers in 3D space. These markers can be reflective markers, reflecting light waves back to the sensors of the system, or active markers actively directing light waves to the sensors. These systems also determine directional vectors of rigid bodies when the markers are attached to them.
A three-dimensional optical digitizer (such as the 3D Creator™ system from Boulder Innovations Group, Inc. of Boulder, Colo.) obtains x, y, z, coordinates of a marker by triangulation using optical sensors arrayed along a baseline. When the distance to the marker is much greater than the length of the baseline, the accuracy of the distance coordinate (typically the z coordinate) is diminished over that of the transverse coordinates (typically the x and y coordinates).